Issues w/ my new 01 Tige - Suggestions?

[XXticy]

Well, just purchased an 01 Tige 21i with 5.8L MPI Merc and thought I did everything right. Test drive in the boat for over an hour and it ran fine, took it to a reputable marine dealer and compression test, and all other checks went fine. Get it to the lake off the trailer and give it gas and it just sputters and won't gain power. If I give it WOT it will pick up and once moving at about 20MPH or more it's fine. As soon as I pull the throttle back it sputters and loses power w/ the low oil pressure warning beep coming on. Only way to resolve is turn engine off let set for 30sec or so and then fire it up. It will idle for about 15-30 sec then the low oil pressure warning goes off again. Boat just had a new fuel pump put on in June 2010. After researching I am thinking it might be fuel filter, idle air control valve, or anti-siphon valve. Am I on the right track with this? Is this something I should take in to the shop or is it fairly easy to fix these on my own?

Thanks...

[dogbert]

When you say low oil pressure warning, are you referring to the light on the dash? If so, that's normal when in gear and below 1000 RPMs.

As for the sputtering, I'd have your reputable marine dealer check the code that the engine is throwing. It'll tell you what's wrong.

[giers]

Had similar issue with my 2002 20i. Took it to my local repair shop and he found that there is a switch from the oil sending unit that shuts off the fuel pump. In my case the wires were corroded and the switch was dirty. Cleaned the wires and switch and all seems to be running great.

Not sure what the part is called or if yours has the same thing but seems to have fixed my problem.

[XXticy]

Dogbert... When I am referring to the low oil pressure I should be more specific. There wasn't a light involved, just my visual observation of the oil pressure falling to 20 "red zone" and the constant beeping of the oil pressure warning until i turned the boat off. All other gauges were in normal ranges and didn't see the temp over 160ish. The boat had just left the local ski nautique shop two days before I took it out and they said it wasn't showing any error codes, had great compression, etc. They ran it for 30min in the shop and also on the lake for a bit. Also said the Tac was showing 4600RPM with WOT.

[dogbert]

When did the oil get changed last?

[kko]

Check oil level and condition. Could just be a faulty oil press. sensor (pretty common). And like giers said that oil pressure switch can affect the fuel pump running so I would start there for sure.

[XXticy]

Well, i have receipts from the previous owner that show the following:

June 2010: New oil filter & oil, fuel filter, & transmission fluid changed

Late June 2010: New fuel pump, plugs, plug wires, & impeller

Mid July 2010: Pre-purchase inspection at reputable marine shop showing good compression test and ran fine in shop for 30min and on water for 30min.

So for an update * Went to get the boat to move to a local shop to have them check it out again. When I was cranking up the trailer to get it on my hitch the whole mechanism broke off the trailer and the tongue crashed to the ground... Had to get someone w/ a floor jack to get it onto the hitch on my truck. Then once I got it to the shop had to have them drop it off the truck with a jack, lol... The joys of buying a used boat. Hopefully it's a simple fix and we can get everything sorted out w/ out having to pay through the nose. Thanks for all the advice

[dogbert]

Make sure they tell you what the code is.

[boatwakes]

The oil beep is coming on because the rpms drop to a low level and cause the oil pressure to fall within the unsafe zone. To determine if its a fuel related issue, attach a fuel pressure gauge (0-50psi) to the fuel rail where the schrader valve is located (looks like a bike tire inflation valve, may have a cap on it too). Your fuel pressure should be at 29-32psi all the time when the engine is running. If it falls, you can start looking at the fuel system, if it stays, you'll be on to the IAC(idle air control) or Throttle position sensor. If it's above that number, the fuel pressure regulator is at fault. However, if its fuel related, the anti-siphon is not a likely culprit, they usually prevent loaded runs at high rpm (loaded=in gear, not high rpm in neutral)by not allowing enough fuel to flow from the tank. Good luck!

[XXticy]

*Update*

Well, as you can tell from the initial date I posted this we bought our 2001 21i in mid July and had issues from the start. After nearly 2 months in the shop the following has been accomplished:
1. New Fuel Pump & Filter (shop)
2. New fuel injector (shop)
3. New IAC (shop)
4. New oil and filter (I accomplished)
5. New hitch, break lines on trailer

After nearly $2k in parts and labor later I got to take the boat out again early September... The backfiring and sputtering has been eliminated, thank god. I am however still getting the alarm for the oil pressure to go off after I have ran the engine for a while, say across the lake. It seems the oil has to 'warm up' before I get the pressure to drop to around 20psi, the top of the "red" on the gauge, and set the alarm off. Temp is normal and I think the oil pressure is safe and not completely dropping off. Any suggestions?
Other issue I had today was after 4hrs on the lake and heading back to the dock some 15min away the boat just lost power. I went from about 35mph and just started slowing down on its own. I pulled it to idle and it cut off. Engine would sound like it wanted to turn over but never would start. Had my buddy tow us in the rest of the way. We did take one wave over the bow when wakeboarding but that was 2 or so hrs earlier. Any suggestions would be greatly appreciated.

[Ewok]

How long did the boat sit before you bought it? It might be something simple like bad gas. If you can, drain the gas tank as much as possible, fill it with fresh stuff, treat it with marine stabil or sea foam, might need to change the fuel filter one more time and see if that helps the boat droping into idle. Bad gas (varnish) does bad and weird stuff to engines.

As for the engine oil pressure? No idea. You might have some particulate material clogging the lines? Have you tried getting a sample of the engine oil analyzed for particulate matter? You could try putting a big magnet on the side of the oil filter, just shooting from the hip here.